Specifically, varenicline may increase blood pressure, heart rate, as well as ratings of dysphoria and nausea.

Varenicline is an effective smoking-cessation medication that may also reduce drinking. However, the means by which it might reduce drinking is unclear. A study of the effects of varenicline on subjective, physiological, and objective responses to low and moderate doses of alcohol among healthy social drinkers has found that varenicline may reduce drinking by increasing alcohol's aversive effects.

Results will be published in the May 2012 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"Varenicline was first approved in the USA for treatment of nicotine dependence in 2006," said Emma Childs, research associate at the University of Chicago as well as corresponding author for the study. "Smokers who use varenicline are approximately two to three times more likely to remain abstinent six months or more after their quit date. After it was approved, several patients treated with varenicline also reported reductions in their drinking, so investigators began to assess if this was an actual effect and how it might be produced."

"Since there is a high comorbidity between nicotine and alcohol dependence, a single medication that could decrease the use of both substances would be ideal," added Hugh Myrick, associate professor of psychiatry as well as vice chair of the Psychiatry Practice Plan at the Medical University of South Carolina.

Childs and her colleagues assessed 15 healthy participants (8 males, 7 females) during six randomized sessions: three sessions each with 2 mg varenicline and placebo, followed three hours later by a beverage containing placebo, a low dose of alcohol (0.4g/kg), or a high dose of alcohol (0.8g/kg). Measures included subjective mood and drug effects such as stimulation and drug liking, physiological measures such as heart rate and blood pressure, and the results of eye-tracking tasks before and after drug and alcohol administration.

"We found that varenicline increased the unpleasant effects of alcohol and decreased drug liking," said Childs, "thus we think that varenicline may reduce drinking by altering the effects of alcohol."

"There are generally two ways that a medication may help reduce alcohol use," observed Myrick. "First, the rewarding aspects of alcohol could be reduced. An example of a medication that works by reducing reward is naltrexone, which blocks opiate receptors and therefore reduces the rewarding aspects of dopamine in the ventral striatum. Second, the aversive aspects of alcohol could be increased. In other words, the medication would cause symptoms leading to a decrease in alcohol use. Disulfiram, or Antabuse, is a medication that works by causing aversive effects if alcohol is consumed. Varenicline may work in a similar fashion."

"Our findings shed light on the mechanism underlying why people consume less alcohol when they have taken varenicline," said Childs. "The pleasurable effects of alcohol, for example feeling 'buzzed' and talkative, are associated with greater consumption and binge drinking. Some people lose control of their alcohol consumption during a drinking episode, for example they may aim to only have one or two drinks but end up drinking say four or five. If varenicline counteracts these positive effects by producing unpleasant effects, then as a result people may consume less alcohol during a drinking episode."

"Varenicline may find a nice niche in those individuals who are both nicotine and alcohol dependent," noted Myrick, "who we know represent a large portion of alcohol-dependent individuals."

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Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. Co-authors of the ACER paper, "Varenicline Potentiates Alcohol-Induced Negative Subjective Responses and Offsets Impaired Eye Movements," were: Daniel J.O. Roche and Andrea C. King of the Committee on Neurobiology at The University of Chicago; and Harriet de Wit of the Department of Psychiatry and Behavioral Neuroscience at The University of Chicago. The study was funded by the National Institute on Drug Abuse, and the National Institute on Alcohol Abuse and Alcoholism. This release is supported by the Addiction Technology Transfer Center Network at http://www.ATTCnetwork.org.

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